This invention relates in general to processes for forming semiconductor devices, and more particularly, to processes for forming semiconductor devices having a deposited layer.
High-k dielectrics are needed for capacitors used in semiconductor devices having design rules at or below 0.25 micron. A problem in forming these capacitors has been the unintentional oxidation of conductive plugs that are used to electrically connect the capacitors with other circuitry within the semiconductor device. When forming the capacitor, a first electrode is typically deposited over the conductive plug. The first electrode may have materials incompatibility issues with the conductive plug, or the first electrode may not adequately protect the underlying conductive plug from being oxidized during a subsequent deposition process step or an oxidizing anneal process step typically needed for the high-k dielectric.
A conductive barrier layer may be placed between the bottom electrode and the conductive plug. However, most barrier layers do not always adequately protect the conductive plug from being oxidized because oxygen from the subsequent deposition or anneal process can diffuse to the conductive plug and oxidize it. In addition, most conductive barrier layers that are used within the semiconductor industry cannot withstand annealing temperatures higher than approximately 550xc2x0 C. At higher temperatures, the barrier layer may partially or completely oxidize, thereby forming a series capacitor with the storage capacitor, and therefore, degrading the overall capacitance density of the device. Additionally, severe oxidation of the plug material may result in a catastrophic failure of the device due to the physical expansion of the oxidized plug material.